Spark-plug



L. S. FLATAU. SPARK PLUG" APPLICATION FILED OCT. 28, [918.

Patented Sept. 14,1920.

ATTORNEYS.

u lTE-osTATEs PATENT OFFICE.

LOUIS S. FLATAU, OF ST. LOUIS, MISSOURI, ASSIGNOR F ONE-THIRD TO ISAAC A.

HEDGES, OF WEBSTER GROVE, MISSOURI, AND ONE-THIRD BENECKE, OF ST. LOUIS, MISSOURI.

ro LOUIS A.

SPARK-PLUG.

Application filed October 28, 1918. Serial No. 260,046.

- To all whom it may concern:

Be it known that I, LOUIS S. FLATAU, 'a citizen of the United States of America, a

resident of the city of St. Louis, in the State. of Missouri, have invented certain new and useful Improvements in Spa'rk- Plugs, of which the followin is a full, clear, and

exact description, reference being had to the accompanying drawings, forming a partof this specification. 1

My invention relates to improvements in spark plugs, one of the objects being to provide a highly efficient spark plug having its electrodes so formed and arranged that the current passing from the inner electrode is it distributedaround the lower margin of said electrode and then discharged across an annular'spark ap between the inner and outer electrodes. ith this object lII VIGW, the

new device comprises a particular "combinat1on and arrangement of elements which most effectively cooperate with each other, as will be hereinafter described. Another object is to enable the inner electrode to properly cooperate with the outer electrode in forming the annular spark gap, even though the inner electrode is not accurately located at the center of the outer electrode.

With the foregoing and other objects in' view the invention comprises the novel construction, combination and arrangement of parts hereinafter more specifically described and illustrated in the accompanying draw- .ings wherein is shown the preferred embodiment of the invention; however, it is to be understood that the invention comprehends changes, variations and modifications which come within the scope of the claims hereunto appended.

' Figure I is a vertical section'of a spark plug embodying the features of this inven tion.

- F i. II is a horizontal section taken approximately on the line' IIII, Fig. I;

Fig. III is a detailview of the inner electrode.

Thespark plug herein shown comprisesv an insulator 1 having a tubular lower portion 2, an inner electrode A extending a tubular outer electrode B in which the insulator is secured by means of a bushlng 3. The insulator has a'shoulder 4 adjacent.

to the bushing and a shoulder 5 adjacent to a corresponding shoulder 6' on the outer electrode. A gasket 7 may be interposed-be- I be ti htened tofirmly .secure the insulator. .The ower portlon of the outer electrode B is threaded at 9 for a stood in this art.

The lower portion of the outer electrode B is provided with an i nition chamber 10 and an annular web 11. forming an annular bottom wall for said chamber. This annular web 11 is preferably formed integrally with the outer electrode, and its central opening 12 is preferably formed at the center line of the spark plug. I

The inner electrode A comprises a solid wire-like member 13 closely fitted to the insulator, and a relatively large portion 14 extending through and projecting downwardly from the tubular lower portion of the insulator. This relatively large member 14 is provided with a hollow cylindrical lower margin 15 having a sharpened annular lower edge which lies within the ignition chamber 10 at a point adjacent to the circular wall of the o ening12, so as to provide an annular spar gap between said shar ened lower edge and said circular wall. it is important to observe that the lower edge of the central electrode lies entirely above the web 11, and that said electrode may therefore occupy a position eccentric to the outer electrode, without short circuiting the electrodes and without materiall impairing the efliciency of the plug. he lower purpose well underportion of the innerelectrode is rigid and inner electrode will usually occupy a position slightly eccentric to the outer electrode. The relatively large' portion 14 of the inner electrode may be screwed onto the lower end of the wire-like member 13, as shown in the drawings. A shoulder is thus formed at the upper end of the large member 14, and this shoulder engages the insulator to limit the upward movement of the r inner electrode relative to the insulator. 1o

designates a nut mounted on the extended upper end of the wire-like member 13 and cooperating with the enlarged lower member 14: to secure the inner electrode to the insulator. A washer 17 may be interposed between the nut 16 and the upper end of the insulator. l8 designates an ordinary binding nut mounted on the threaded upper end of the inner electrode.

As shown most clearly in Fig. I, the inner electrode is solid throughout its length, excepting at its lower margin where it is preferably drilled to form the cylindrical portion 15. The electric current passes downwardly through the solid portion of the inner electrode and thence to the cylindrical lower portion 15, where it is distributed from the center of the electrode and transmitted to the annular lower end thereof. Owing to this manner of distribution and delivery of the current, or to some resultant electric phenomenon which I am unable to fully explain, the sparks pass from the lower end of the inner electrode so as to form an annular frame in the annular spark gap. The sparks do not merely jump acrossthe path of least resistance, as is usually the case where a solid electrode is surrounded by an annular shoulder. Comparative tests have clearly shown that a spark gap formed as herein shown is far more eflicient than a sparking device having a solid central electrode. I have also found that the sharp lower edge of the central electrode increases the eiliciency of the device. Furthermore, the inner electrode having its lower end arranged entirely within the ignition chamber 10 may he accidentally displaced transversely of the plug without very materially impairing the eiiiciency of the plug. Then a plug of this kind is applied to an internal combustion engine, some of the explosive mixture will be forced into the ignition chamber 10, where it will be quickly ignited by the sparks, with the result of producing a flame at the opening 12. thereby facilitating the complete ignition of the charge.

I claim:

1. A spark plug comprising an insulator, an inner electrode extending through said insulator, an outer electrode in which said insulator is secured, the lower portion of said outer electrode being provided with an ignition chamber and an annular web forming an annular bottom wall for said chamber, said inner electrode having a hollow lower end which lies entirely within said ignition chamber at a point above, but adj acent to, the circular wall of the opening in said annular web, so as to provide an annular spark gap between said hollow lower end and said annular bottom wall.

2. A spark plug comprising an insulator, an inner electrode extending through said insulator, and an outer electrod in which said insulator is secured, the lower portion of said outer electrode being provided with an ignition chamber and an annular web forming an annular bottom wall for said chamber, said inner electrode havin a relatively large lower portion providec with a hollow cylindrical lower margin which lies within said ignition chamber and above said annular web, said cylindrical lower margin being above, but adjacent to, the circular wall of the opening in said annular web, so as to provide an annular spark gap between said cylindrical lower margin and said annular bottom wall.

3. A spark plug comprising an insulator, an inner electrode extending through said insulator, an outer electrode in which said insulator is secured, the lower portion of said outer electrode being provided with an ignition chamber and an annular web forming an annular bottom wall for said chamber, said inner electrode comprising a solid wire-like upper member closely confined in said insulator and a relatively large lower member extending downwardly from said solid upper member, said relatively large member being provided with a cylindrical lower'end portion having an annular lower edge which lies entirely within said ignition chamber and above, but adjacent to, the circular wall of the opening in said annular web, so as to provide an annular spark gap between said annular lower edge and said annular bottom wall.'

4. A spark plug comprising an insulator having a tubular lower portion, an inner electrode extending through said insulator and projecting downwardly from the tubular lower portion thereof, an outer electrode in which said insulator is secured, the lower portion of said outer electrode being provided with an ignition chamber and an annular web forming an annular bottomwall for said chamber, the lower portions of said insulator and inner electrode being inclosed by said ignition chamber, said inner electrode having an enlarged lower end portion provided with a hollow cylindrical lower margin and a relatively sharp annular lower edge which lies entirely within said ignition chamber and above, but adjacent to, the circular wall of the opening in said annular web, so as to provide an annular spark gap between said sharp annular lower edge and said annular bottom wall.

5. A spark plug comprising an insulator having a tubular lower portion, an inner electrode extending through said insulator and projecting downwardly from the tubular lower portion thereof, an outer electrode in which said insulator is secured. the lower portion of said outer electrode being provided with an ignition chamber and an annular web forming an annular bottom wall for said chamber, the lower portions of said 1.85am a v insulator and inner electrode being inclosed by said ignition chamber, said inner electrode comprising a solid wire-like 11 per member closely confined in said insu ator and provided with a screw threaded lower end, and a relatively large lower member screwed onto said threaded lower end, said relatively large member having a hollow cylindrical lower margin and a relatively shar annular lower edge which lies entirely within said'ignition chamber and above, but adjacent to, the circular wall of the opening in said annular web, so as to provide an ana nular spark gap between said sharp annular lower edge and said annular bottom wall.

6. A spark plug comprising an insulate an inner electrode extending throu h sai insulator and projecting downwar y' from the lower portion thereof, and a hollow outer electrode in which said insulator is 20 secured, the lower rtionof said outer electrode being provi ed with an annular bottom wall, and said inner electrode "being provided with a hollow lower end having a shar. lower mar circ lar inner wall. to form an annular spark? gap.

. In; testimony that I claim the foregoing'l hereunto afiix my si ture. i a UIS 'FLATAU.

located adjacenttotbp it ge of said annular 

